The present invention relates to a navigation system, more specifically to a navigation system that stores trail data of a vehicle traveling off-road, displays the off-road travel trail of the vehicle appropriately on a display screen, and sets a destination by means of the off-road travel trail data.
A navigation system detects the position of a vehicle and reads out map data of the area surrounding the vehicle from a map storage medium such as a CD-ROM or a DVD, displays the image of the map data on a display screen, and superimposes a vehicle mark (the user""s own vehicle mark) with the map image at a specified position on the display screen. As the current position of the vehicle varies with the movement thereof, the navigation system moves the vehicle mark on the screen, or fixes the vehicle mark at a specific position such as the screen center and scrolls the map image, so that the driver can recognize the map information surrounding the vehicle position at a glance.
This type of navigation system is provided with a travel route display function that superimposes the route on which the vehicle traveled in the past with the map image on the screen. The travel route display function stores the vehicle position (longitude and latitude) in a travel route memory as discrete travel route data, each time the vehicle position detected by the vehicle position detector varies by a constant distance, while drawing the map image on the screen, selects data to be taken in as the map image data from the discrete travel route data stored in the travel route memory, and identifiably draws the map image by changing the sequence of points or the color at a corresponding position on the map image.
Therefore, because it can display the route on which the vehicle traveled in the past with the sequence of points on the road in the display screen, the navigation system having the travel route display function can easily bring the driver back to the point of departure, for example, by tracing back the travel route on the return, even if the driver travels to an unfamiliar place. In addition, if the driver travels again to the same place later, the driver can easily reach the place on the outward journey by re-tracing the travel route.
However, the conventional navigation system stores the travel route only when traveling on roads, and does not have a function to store the travel route when traveling in off-road areas and display the travel route in the off-road areas. In the United States, for example, which has vast natural terrain, many users of the navigation system travel off-road. For example, they go deep in the mountains by jeep to camp or hunt deer or pheasants, they drive about in the desert or wilderness where no roads are available, they go to summer cabins without accessible roads deep in the mountains, and the like. On some later occasions, they may return to the cabin, campground or hunting area, where they once traveled. However, since the conventional navigation system does not have a function to store the travel trail in the off-road areas, it has been difficult for users to reach the cabins or campgrounds. That is, the off-road travelers have a desire to store the off-road trails, to view the trails afterwards, and to re-trace the trails once again, which the conventional navigation system could not do.
It is therefore an object of the invention to provide a navigation system that displays an off-road travel trail afterwards.
Another object of the invention is to make it possible to store an off-road travel trail automatically or only when a user instructs, and to read out and display a desired travel trail afterwards.
Another object of the invention is to make it possible to automatically store an off-road travel trail from an off-road point (entry point to an off-road area from an on-road area) to an on-road point (entry point to an on-road area from an off-road area).
Another object of the invention is to make it possible, when the vehicle travels along an off-road travel trail and deviates from the off-road travel trail, to automatically store the travel trail after the deviation.
Another object of the invention is to make it possible to register an off-road point and an on-road point as an entrance to the off-road trail to thereby search and display a guide route to a specific off-road entrance.
Another object of the invention is to make it possible to register an off-road travel trail in association with a place name of a destination or transit point on the off-road travel, to thereby set a destination easily from a list of the place names afterwards and display the map or the travel trail surrounding the set destination afterwards.
Another object of the invention is to make it possible, when a place name as a destination of an off-road travel trail is set, to search and display a guide route to the off-road entrance, or to call a facility associated with the place name by a mobile telephone.
Another object of the invention is to make it possible to display a remaining capacity of the memory that stores the travel trail, for example, by a distance.
The navigation system of the invention includes: (1) a position measurement unit that detects the user""s own vehicle position, (2) a monitoring unit that monitors whether the vehicle position deviates from a road so as to be in an off-road state, (3) a travel trail generating unit that generates off-road travel trail data, when the vehicle is in the off-road state, and (4) a storage unit that stores the travel trail data. That is, the navigation system of the invention stores the off-road travel trail data in memory, and the user is able to read out desired off-road travel trail data and to display the travel trail appropriately.
In another aspect of the navigation system of the invention, in storing the travel trail data, the user sets whether to generate the off-road travel trail data automatically or to generate the data by an instruction from the user. If the setting is automatic, when the vehicle is in the off-road state, the system automatically generates and stores the off-road travel trail data from the off-road point to the on-road point. With this construction, the system achieves enhanced maneuverability and secure storage of the off-road travel trail. On the other hand, if the setting is to generate the data by an instruction from the user, the system begins to generate the off-road travel trail data by a generation starting instruction, and terminates the generation of the off-road travel trail data by a generation terminating instruction, and stores the data. With this construction, the system does not produce the travel trail data when the vehicle is in an area where the travel trail is not needed to be stored, such as shopping malls, public gardens, etc. Therefore, the system achieves effective use of the memory and does not store unnecessary travel trail data, and the user is able to easily retrieve and/or edit the data afterwards.
In another aspect of the navigation system of the invention, when the user travels along an off-road travel trail and the vehicle position deviates (branches) from the off-road travel trail, the system produces the position data of the branch point and the travel trail data after branching in association with the name of the branch point, and stores these data. With this construction, the user is able to search the destination by entering the branch point.
Further, since the navigation system of the invention can register an off-road point and an on-road point as an off-road entrance, the user can select either one of them and cause the system to search and display a guide route to a specific off-road entrance.
Moreover, since the navigation system of the invention can register an off-road travel trail in association with the destination of an off-road travel or the place name of a transit point on the off-road travel, the user is able to set the destination easily from a list of place names, and to display the map and the travel trail surrounding the destination thus set.
In another aspect of the navigation system of the invention, when the user selects the destination of an off-road travel or the place name of a transit point on an off-road travel and instructs a call, the system causes the automobile telephone to call a facility at that location. Thus, the user is able to call facilities located inside the off-road area with an easy operation.
Further, the navigation system of the invention monitors the remaining capacity of the memory to store travel trail data, and displays the remaining capacity by means of a storable remaining point number or a storable remaining distance. Thus, the user is able to delete unnecessary off-road travel trail data by editing, when the remaining memory capacity diminishes, and to store only the necessary trail data.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings.